Actually since I believe it requires the latest u-connect update, the one with Siri, it may actually be possible without a subscription. They may have updated the u-connect to call home using the 3g on a schedule.
I would also guess that the signal would have to originate from your vehicle in order to do the connection if needed. That alone is scary/helpful as it could conceivably allow FCA to upload vehicle information on how its performing and any error codes in the system. That would further allow them to send notices of needed service or system failures. Helpful to many that ignore basic things on their vehicle. Also helpful to FCA in the area of tort.
If I have not stretched this too far your vehicle and driving habits will be in the cloud soon. That alone would more than pay for the 3g service of updates.
Especially when they get the income for selling that information to the insurance companies......